GaInNAs/GaAs量子阱的光致发光谱和光调制反射谱

Investigation of Photoluminescence and Photoreflectance in MBE-Grown GaInNAs/GaAs QWs

研究了 Ga In NAs/Ga As多量子阱在不同温度和激发功率下的光致发光 (PL )谱以及光调制反射 (PR)谱 .发现 PL谱主发光峰的能量位置随温度的变化不满足 Varshni关系 ,而是呈现出反常的 S型温度依赖关系 .进一步测量 ,特别是在较低的激发光功率密度下 ,发现有两个不同来源的发光峰 ,它们分别对应于氮引起的杂质束缚态和带间的激子复合发光 .随温度变化 ,这两个发光峰相对强度发生变化 ,造成主峰 (最强的峰 )的位置发生切换 ,从而导致表观上的 S型温度依赖关系 .

Photoluminescence (PL) and photoreflectance (PR) spectra of GaInNAs/GaAs multiple quantum wells (MQWs) grown on GaAs substrate by MBE are measured over a range of temperature and excitation power density.The energy position of dominant PL peak shows an anomalous S shape temperature dependence instead of Varshni relation.By the careful inspection,especially for the PL under lower excitation power density,two near band edge peaks are well identified.They are assigned to carriers localized by nitrogen induced bound states and interband excitonic recombinations respectively.It is suggested that the temperature-induced switch of such two luminescence peaks in relative intensity causes a significant mechanism responsible for the observed S shape shift in GaInNAs.A quantitative model based on the thermal excitation and depopulation of carriers is used to explain the temperature dependence of the PL peak related to N induced bound states.